A model can be generated to represent a subterranean structure, where the subterranean structure can be a reservoir that contains fluids such as hydrocarbons, fresh water, or injected gases. A model of a reservoir (“reservoir model”) can be used to perform simulations to assist in better understanding characteristics of the reservoir. For example, well operators can use results of simulations based on the reservoir model to assist in improving production of fluids from the reservoir. The reservoir model can be used as part of a production optimization workflow that is designed to improve production performance.
Conventional reservoir models are typically “detailed” or “fine” reservoir models. A detailed or fine reservoir model includes a relatively fine grid of cells that represent corresponding volumes of the subterranean structure. Each of the cells of the reservoir model is associated with various properties that define various characteristics of the formation structures in the volume.
The number of cells selected for a detailed reservoir model typically is based on the available computational power provided by a computer system used for performing a simulation using the detailed reservoir model. For improved accuracy, the granularity of the grid of cells that make up the detailed reservoir model is selected to be as fine as practical. The operator typically attempts to discretize the model to as fine a grid as possible such that a simulation using the detailed model can complete its run overnight (execution time of greater than eight hours, for example).
Although a detailed reservoir model can provide relatively accurate results, use of a detailed reservoir model may not be practical or efficient in certain scenarios due to the relatively long computation times. Also, development of detailed reservoir models may not be cost effective, particularly for reservoirs that are considered marginal reservoirs (those reservoirs that are not expected to produce a large volume of fluids, that are relatively small, or that are approaching end of life). Moreover, using a detailed reservoir model in a production optimization workflow can slow down execution of the overall workflow, since the simulation of the detailed reservoir model can take a rather long time to complete. A user of the production optimization workflow may desire to obtain answers quickly when performing an optimization procedure with respect to a field of one or more production wells.